Update payment.d.ts

[Smoggert]

Adds the missing type definitions for defaultValues in case of the PaymentElement

Summary & motivation

Related issue: https://github.com/stripe/stripe-js/issues/627

Testing & documentation

I did not test this. Feel free to do so though.

https://docs.stripe.com/js/elements_object/create_payment_element#payment_element_create-options-defaultValues

[CLAassistant]

All committers have signed the CLA.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.